Question

What is the empirical formula of a substance that contains 2.64g of C, 0.444g of H, and 3.52g of O?

A) C₂H₄O₃
B) CH₂O
C) C₂H₄O₂
D) C₃H₄O₄

Answer 1

To find the empirical formula, convert the given masses to moles, divide by the smallest number of moles to get a whole number ratio, and deduce the formula CH₂O from the ratio.

Step-by-step explanation:

To determine the empirical formula of a compound using mass percentages, we first convert the mass of each element to moles by dividing by the element's atomic mass (C = 12.01 g/mol, H = 1.008 g/mol, and O = 16.00 g/mol). For the given mass of C (2.64 g), H (0.444 g), and O (3.52 g), we find:

• C: 2.64 g / 12.01 g/mol = 0.22 mol
• H: 0.444 g / 1.008 g/mol = 0.44 mol
• O: 3.52 g / 16.00 g/mol = 0.22 mol

Next, we divide each mole value by the smallest number of moles calculated to get the simplest whole number ratio:

• C: 0.22 mol / 0.22 mol = 1
• H: 0.44 mol / 0.22 mol = 2
• O: 0.22 mol / 0.22 mol = 1

The ratios give us one carbon atom to two hydrogen atoms to one oxygen atom, which results in an empirical formula of CH2O, option B).